Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
hanh di » hanh de, hang di, danh di
hieu ve » hieu va, hieu van
cuu tre » cua tre, cau tren, cau treo
sach v » sach va, sach y, sach vay
ve cam » ve cham, ve cac, va cam
sach 2 » sach y
x hoi » xa hoi, o hoi, x ho

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach v) OR (sach 2)) nang x hoi. hieu ve cam thuc vat ((hanh di) or (hanh vi)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach v) OR (sach 2)) nang x hoi. hieu ve cam thuc vat ((hanh di) OR (hanh vi)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach v) OR (sach 2)) nang x hoi. hieu ve cam thuc vat ((hanh di) or (hanh vi)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach v) OR (sach 2)) nang x hoi. hieu ve cam thuc vat ((hanh di) or (hanh vi)) cuu tre*.